Recent progress in vaccine development offers hope that immunization can slow the HIV-1 epidemic. Insights into immune mechanisms of protection against HIV-1 infection and diseases are emerging in clinical and animal studies, which can be applied to immunization strategies. New vaccines designed to elicit these immune responses are rapidly becoming available for implementation in human trials worldwide. Despite these advances, it remains unclear which approach is more likely to be efficacious, and if so, by what mechanism. The overall goal of this symposium is to accelerate understanding of the components necessary to prevent HIV-1 infection by vaccination, and to stimulate the scientific field at all levels to participate in moving this effort forward. The forum provides a unique opportunity for scientists with a broad range of expertise to exchange new ideas and to discuss recent findings. More importantly, the open and warm Keystone setting fosters interactions between young investigators with the scientific leaders in the field. The symposium will educate and engage those persons in training to pursue areas of HIV-1 vaccine research and will provide renewed commitment for those investigators already dedicated to vaccine development.